Carburetor



-May 12, 1936.

J. w. Frrz GERALD CARBURETOR Filed Aug. 13, 1934 QM fa/727 ME/ZE FE/U QM v v r 313 v Patented May 12, 1936 UNITED STATES,

CABBUBETOR John W. Fits Gerald, Milwaukee, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Win, a corporation of Delaware Application August 13, 1934, Serial No. 739,625

3 Claims. (01. 261-52) This invention relates to an automatic control of the gas mixture created by a carburetor employed in association with internal combustion es. The standard carburetor is generally equipped with an accelerator pump for the purpose of supplying additional fuel during acceleration. 'Ihe plunger of the pump is attached to the throt- -tle so that in operation, a rapid or quick opening of the throttle causes an immediate discharge of the gasoline within the pump and. does not supply a constant, steady continuous quantity of additional gasoline for utilization by the engine and consequently, the fuel-air mixture is not enriched by this additional gasoline for a long'enough period to satisfy the operating demand of the engine. -Again, if the acceleration isslow, then the additional supply is not needed, and still the same amount of'gasoline is fed by the pump to the carburetor. 7 With the foregoing difllculties in mind, it is the primary purpose of the present invention to provide automatic control of the gasoline mix- ,ture created by a carburetor, to the amount needed for emcient carburetion during any stage or condition of engine operation.

It is another object of the invention to provide a simple and eflicient means for increasing the fuel ratio of the gasoline mixture of a carburetor upon sudden,or quick acceleration, by automatically lessening the air content thereof, as by closing the choke valve.

' With the above and other objects in view which will appear as the description proceeds this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particular y defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

7 The accompanyin drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode .aofar devised for the practical application of the principles thereof, and in which:

Figure 1 is a side elevation of a conventional carburetor illustrating the application of the present invention thereto; and v t Figure 2 is a cross-sectional view taken on the plane of line 2-2 of Figure 1.

Referring now' more particularly to the mom-- panylng drawing, the numeral indicates generally the conventional carburetor in which there isaliixing chamber 6, an air intake 1 provided with a butterfly valve 8, commonly known as a. choke valve, a jet for the carburetor (not shown), and the conventional passageway above said jet having therein a throttle valve 9.

The throttle valve 9 is controlled in the con- 5 ventional manner by means of an accelerator (not shown), and to afford the desired control of the choke valve 8 to effect an enrichening of the mixture during rapid acceleration, the choke valve 8 is connected with the throttle control as 10 now about to be described.

Attached 'to the throttle valve stem Ill is a lever ll connected to the rod l2 of a piston 13.

The piston l3 operates in a cylinder l4 which is slidably positioned within a guide IS. The guide I! as shown in Figure 2 is cast as an integral part of the carburetor. However, it is apparent that.

the guide I5 might be a separate unit and need only be fastened securely to the carburetor.

At the lower end of the cylinder I4 is an air outlet l6.-controlled by a needle valve ii. The lower wall [8 of the cylinder l4 has cast thereon a boss I9 to which is attached a link 20, the other end of which is pivoted as at 2| to a choke lever 22, which in turn is fixed to the choke valve stem 23. A torsion spring 24 coiled about the stem 23 with one end bearing against a stud 25 positioned on a boss 26 and its other end engaged in a notch 21 in the lever 22 normally holds-the choke valve 30 open. a

From the description thus far, it will be apparent that the piston l8 reciprocates simultaneously with any adjustment of the throttle valve. If the adjustment of the throttle valve is effected slowly, the piston merely reciprocates in its cylinder without in any wise affecting the position of the choke valve since the air displaced by the piston escapes through the air outlet It. In the event the throttle valve is opened suddenly, a consequent sudden depression of the piston l3 occurs with the cylinder l4 moving with the piston inasmuchas the air contained within the cylinder chambercannot escape through the air outlet rapidly enough to permit the piston to move within the cylinder. -As a result of such sudden acceleration, the choke valve 8 will be closed against the action of its spring 24 to a degree dependent upon the suddenness of acceleration and the adjustment of the needle valve ll, and upon the'closure of the choke valve, the fuel mixture is of course enriched, thus affording the proper mixture during the actual acceleration. As will be readily apparent, the spring 24 will return the choke valve to its normal open position even though the throttle valve is held fully nection with the accompanying drawing, it will readily appear to those skilled in the art to which this invention appertains, that there is aflorded thereby an eflicient means to automatically coordinate the richness of the fuel mixture with the varying requirements of the operation of the engine.

What I claim as my invention is:

1. In a carburetor having a fuel supply and an air supply, a choke valve to control the air supply, a spring reacting against a fixed abutment and acting upon the choke valve to bias the same tov ward open position, a throttle valve to control the flow of carbureted fuel-air mixture from the carburetor, means for opening and closing the throttle valve, and a connection between the throttle valve and choke valve whereby sudden opening of the throttle valve closes the choke valve while gradual opening of the throttle valve permits the choke valve to remain in its open position, said connection including a cylinder connected with the choke valve to move directly in accordance therewith at all times and to be acted upon by thechoke valve spring, and a piston connected with the throttle valve to move therewith at all times operating in said cylinder.

2. In a. carburetor having a fuel supply and an air supply, a choke valve to control the air supply, a throttle valve to control the flow of carbureted fuel-air mixture from the carburetor, a

connection between the throttle valve and the Y open. The return of the choke valve to its open choke valve whereby sudden opening of the throttle valve closes the choke valve while gradual opening of the throttle valve leaves the choke valve undisturbed in open position, said connection including a cylinder linked to the choke valve to move in unison therewith at all times, a piston sliding in the cylinder and linked to the throttle valve, said cylinder and piston cooperating to provide a dash pot, a spring acting upon the linked choke valve and cylinder and reacting against a fixed support to at all times yieldingly urge the choke valve to open position and the cylinder toward the piston, and a fixed stop abutment to limit the movement of the choke valve and the cylinder linked thereto in a position at which the choke valve is open.

3. In a carburetor having an air supply and a fuel supply, a choke valve for controlling the air supply, a throttle valve to control the flow of carbureted fuel-air mixture from the carburetor, a connection between the throttle valve and the choke valve whereby sudden opening of the throttle valve closes the choke valve while gradual opening of the throttle valve leaves the choke valve undisturbed in open position, said connection comprising a cylinder linked to the choke valve to move in unison therewith at all times and having an open end and a closed end with an air bleed through its closed end, a piston slidable in the cylinder and linked through the open end of the cylinder to the throttle valve, a spring acting upon the linked choke valve and cylinder to yieldingly urge the same in a direction to open the choke valve, and means to constrain the movement of the cylinder and limit its motion under action oi. said spring in a position at which the choke valve is open.

JOHN W. FITZ GERALD. 

